It sounds like you will have to remove the toilet and pull out whatever is lodged in the lower trapway of the toilet. You may be lucky enough to find old combs you thought you had lost, even some of the kids toys they can't find. I generally will take the toilet outside to clean and inspect the toilet. When done, set the toilet up on blocks. Give it a real test with paper towels and pour buckets of water through, to see if you have reacquired the original flush,
Make sure you use enough wax, most of the time two, get new closet bolts, closet caps, and an new supply line between the shutoff and tank connection.